Carl eumpff



rA'rne Artur MANUFACTURE OF BROWN DYE-STUFF.

SPECIFICATION forming part of Letters l atent No. 257,242, dated May 2, 1882.

L Application filed February 18, 1882. (Specimens) To all whom it may concern:

Be it known that I, CARL RUMPFF, residing at Aprath, near Elberfeld, in the Kingdom of Prussia and Empire of Germany, have invented a new and usefullmprovement in Man ufa'cturing Brown Dye-Stuff Suitable for Dyeing Wool and Silkin Fast and Brilliant Shades, of which the following is a specification.

My invention consists of the new observation that the sulphonic acids of alphanaphthylamine, if treated with nitrous acid in a nontral or very weak acid solution, give valuable bro wn coloring-matters, soluble in water,which dye silk and wool in brown shades fast against soap and light, and which are distinguished by an-immense dyeing-power.

It is a well-known fact that alphanaphthylaminesulphonic acid, if treated with nitrous acid in an acid solution, yields diazonaphthalinesulphonic acid-a colorless body. If, however, the naphthylaminesulphonic acid is treated with nitrous acid in neutral or very slightly acid solution, (by preference in an acetic acid solution,) amidonzonaphthalinesulphonic acid is formed, which,like all amidoazo compounds, is a dye-stud.

In carryingout my invention I dissolve one hundred kilograms of alphanaphthylaminesulphonate of soda and fourteen kilograms of nitrite of soda in eight hundred kilograms of water, and add by and by so much of any acid (by preference acetic acid, one part acetic acid and nine parts of water) as will be found necessary to decompose the nitrite of soda. The solution gets immediately darkbrown-colored, and the reaction is finished after one or two days standing, after which time the coloring-matter may be either precipitated with diluted sulphuric 0r hydro chloric acid, or may also be obtained by evaporating the whole liquid to dryness.

In place of nitrite of soda, free nitrous acid may be brought in reaction with the solution of the naphthylaminesulphonic acid, and also, if one molecule of diazonaphthalinesulphonic acid is mixed with one molecule of alphanaphthylaminesulphonic acid in a neutral solution, the brown coloring-matter is formed.

In place of alphanaphthylamine, methyl and naphthylamine may be used.

The different methods for preparing the alphanaphthylaminesulphonic acids are well known. I, however, recommend as the best one that method founded upon heating alphanaphthylamine with two to live parts of oilot' 

